Why are particles set to scale 1.0 way bigger then my Original particle
Final hair particle size is the result of multiplying hair length with particle object scale.

Default hair length is $4$ Blender Units, so to get an object of identical size to the original you have to multiply it by $1/4$, hence $0.25 \times 4 = 1$

If you plan on rendering particles as objects and need easy to set up scales then change hair length to $1$.